Installing a used 39mm FCR-MX on a ’03 640 Adventure

I have just bought an FCR41 MX from a 2007 450 SXF and I am hoping to make this work with my 2003 625 SXC (which currently has a BST-40).

Does anyone know if I will need new throttle cables ?

Also, I will probably order a JD Jetting kit. Am I likely to need anything outside of what they supply in their standard kits ?

Thanks !

Anyone who has a bst at home to get rid of after the switch to a fcr? i am looking for one. thanks

I have the BST40 from a '00 Lc4e that's available. PM sent

I can get fcr40 from 07rmz450 for a good price. Does anyone think it wouldn't work for 00 640?
My reasoning is that 39 and 41 works, why 40 wouldn't work?

Well, I decided to give it a try anyway. Now the question is how to make this work with stock airbox?




Any ideas? I may have to ebay it afterall.

I have that carb also. I just need to clean it up, install the JD Jet kit, and figure out the bell to air box boot that I need. Let us know how it goes, Wes

If that is a 40mm FCR it's the first one I have heard about.

Air box to carb was not a big problem on my 01 LC4-E. I'm thinking the 2000 Adv and my 01 E should have the same boot.

same here, i dont know that you are gonna be able to make that one fit. i wish you lot's of luck though!

laramie

it's from 07 rmz 450. Google it and that's what they have in it.
JDjetting suggested to use 625smc kit and it should work fine.

I think I need to make an aluminum ring adapter to match an existing airbox boot's ID and then epoxy it to the carb. I looked through SUDCO catalog and didn't find right adapter.

My 450 has FCR with 2 threaded holes so you can mount whatever intake you want. Why did they changed it?

Will keep updated. I pull bst out tonight and take some measurements.

PS. This carb also has hot start hole but no actual "pull knob" should I bother with it?

What are the 2 sets of code numbers stamped on the body of the FCR you have? The one I have is from a KTM 450 (from memory) 39mm FCRMX and the numbers are 3900B CRG02 and it only has the black choke knob but no Red hot start knob. I gather the hotstart feature is not critical. Even though mine's a 39mm nominal, when the engine side choke diameter is measured its 40mm!

I think you'll find that you MAY be able to get the "boot" or adapter parts you need if you look at the KTM parts on a fiche for a 625SMC or 450 or similar as those bikes used an FCR.

My fcr p/n is 35G4UG26. I measured OD on BST and air side is 58mm and 46mm on engine side. length is 98mm.
my FCR on air side 54.5mm and engine is 58.5, length is 82mm(16mm shorter).
Engine side almost works, but boot is slightly wider than needed. Could feet if I cut slot for the key on FCR manifold.

Something has to be made for the airbox side.

I kind of put FCR in and it goes very easily into the frame, enough clearance if I pull of crankcase vent hose. Stock cables should work, hopefully.

I don't think there is TPS on my year bike.

I am not sure if any of SXC boot's would work because it was for older FCRs , pre 07. Just look at the 07 525/450 fcrs, different air side and airbox goes directly over it, no additional boots.

From what little I can see. The cylinder end bell side looks kinda strange, or is that two groves instead of the normal single grove?

You will find your air box boot adapter at LOWE'S or some pluming supply store.
I used a 1.5 rubber water pipe cap. I then cut off the cap part leaving a large flat/thick band to fill the small gap between air box boot and carb.
"With care" slide the new band on carb then mate the boot over the band and hose clamp.

The air box boot supports nothing, make sure it is so. All the support for carb is the cylinder head boot.

Somebody has got some nice RED TOES in the pic there ...666. They are not yours, or are they.?

My wife was helping me by walking around and talking hell knows what about something.

I was browsing at lowes this morning and nothing was quite right, but could work. as you suggesting.

Would be nice if some ktm dealer had various cylinder boots in stock, so i could measure them and find the right one. I doubt it's going to happen. Anyone knows such a dealer?

Cylinder side on the carb has two grooves. Same on my 450exc.

Re boots et al, probably worth checking Creepster's original text, ie ....

"The head to carb intake boot.
First, you can run both the original boots… they don’t fit as well as boots for an FCR, but the do fit and you save about $50.
If you do chose to buy the head to carb intake boot, it is in your best interest to buy the corresponding clamps as well. They are narrower by a few mm and smaller in diameter as well.
The BST boot clamps will fit, but they distort the boot shoulders and you can’t tighten down the carb end one enough to get a good, happy-snuggie fit."

Re your diameters 666, I measured the choke or internal diameter of the main air/fuel mix exit port that fis on the engine (not filter) side. 40mm

My FCR39 went on perfectly with the airboot from a 625SXC. 12ish dollars from cheapcycles.com.

Regarding halfcab's suggestion, also check out Ace Hardware. They too have rubber couplings etc which may fit.

Like one of these no hub couplers as a source of rubber.

Unfortunately some of the Creepers original notes don't apply to this carb. The airbox side is completely different, as I mentioned earlier FCR changed from 07 and up.
In this photo I put Black arrow to the airbox side manifold which you can screw on the carb. Well new fcrs don't have it at all.


This is new style FCR sideview. Airbox side is on the right


no tapped holes on the airbox side


So, because of this you can't just buy boot for 625 since it was designed for old style fcr.
I am going to epoxy something to work with original boot.
Cylinder side may work with 625 boot if OD on the old style fcr is the same. Unfortunately I don't have one around to measure

I was at OSH this morning and tryied different rubber couplers, they all were wrong OD or ID.
I'll check some other places.

Even with all these issues it's gonna be much better than BST and worth the trouble. Every time I get on my 450 I can't believe throttle response.

I went though all this a few month ago - yes a pain and yes worth the effort.

The 625 intake will not work that well, It is possible to shimmy it however if,
1. You super glue a strip of 1/8" rubber to the inside to reduce the ID on the carb side.
2. Slide the boot forward on the airbox side till it just catches.
3. Stretch the boot enough to catch the carb intake.
-the 625 Intake boot is an accordian style which makes this possible.

As you've probably discovered the carb is "shorter" front to back than it should be, and the intake side is too small OD.

I did the above, wasn't completely happy and found a post on Thumpertalk about a place (in Kansas I believe) that makes a retrofit intake bell. I went this route and bingo everything fits perfecto - it presses on, you just have to file off the little ridge.

Unfortunately I'm on the road and don't have the link but should be google-able. Best luck.

Just realized I have a couple pics on my camera.
This shows the filing which I did with a dremel - note there is already a PowerNow pressed in.





Don't ask me why I didn't take a side shot, but here is it installed. I put a little silicone on the inside of the bell, but if you're carefull it's a snug press fit and shouldn't leak.

Was it this company http://www.nossmachine.com/fcr_adapters.htm ?